The system is the most visible iteration yet of the future Microsoft hopes to build around Windows 8, its new operating system that promises to run seamlessly on PCs, tablets and smartphones.

SmartGlass is an app for Windows 8, which is currently available in a preliminary beta version. But the system will also work with mobile devices running Apple's iOS and Google's Android operating systems.

"Xbox is on a mission to make the entertainment that you love even more amazing," Don Mattrick, president of interactive entertainment for Microsoft, said at a media event kicking off E3, the world's largest gathering for the video-game industry.

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"With Xbox SmartGlass, we are lighting up entertainment across your phone, tablet, PC and TV in a completely new way. If you love to play games, watch TV and movies, surf the Web or listen to music, there has never been a better time to be on Xbox."

Among its features demoed at the event: using a tablet to call plays on "Madden 2012" and viewing maps of the fantasy land of Westeros on a tablet or smartphone while watching "Game of Thrones" on HBO.

The technology also was used to pause a movie on a Windows tablet and then send it to an Xbox to continue watching -- and as a way to use a smartphone as a remote control.

Industry veteran Adam Sessler, a former G4TV host, thinks SmartGlass could be a savvy move for Microsoft.

"They read the reality of the landscape and realized they can't compete in the tablet market. This allows them to get their stamp on every device with no risk," he told CNN. "It shows a maturity at Microsoft about how people are handling their games and entertainment. I don't think [SmartGlass] works right now for gaming, but I have a few ideas on how it might work for the future."

SmartGlass was the highlight of a list of features emphasizing that Microsoft wants the Xbox, and its Xbox LIVE network, to be far more than just a way to play games.

Saying Web browsers on other networks are "painfully slow," Mattrick announced that an integrated version of Internet Explorer will be coming to the Xbox this fall. And he announced Xbox Music, a service that will bring millions of songs to the console and devices running Windows 8.

But, this being E3, the big excitement at the convention was about the games.

Microsoft began the event with a part-gameplay, part live-action movie trailer for "Halo 4," the latest in the beloved shooter series that has sold more than 40 million copies worldwide. The game is due in November.

That game and other previewed titles like "Splinter Cell: Blacklist" and "Madden 2013" will use the Kinect system's voice controls to let players speak, instead of fiddling with buttons, to give certain commands.

Hall of Fame quarterback Joe Montana was brought out to play some "Madden," calling plays and audibles in real time as he guided the San Francisco 49ers offense.

Other celebrity highlights included Usher demonstrating dance moves he helped craft for "Dance Central 3" and "South Park" creators Matt Stone and Trey Parker talking up "South Park: The Stick of Truth," a video game due to be released in March.

In the game, the player is a new kid in town trying to join the foursome of Stan, Kyle, Cartman and Kenny. The results, of course, are ridiculous.

"The only thing that really interested us was if we could make a game where it felt like you were in an episode of 'South Park,' " Stone said.

Former TV host Sessler said he was impressed with the "really strong" lineup of Xbox games previewed Monday.

"They [Microsoft] were showing that they aren't changing their brand. When the next-gen console comes out, the early adapters are going to be the hardcore gamers," he said. "Those titles spoke directly to them."

Microsoft's presentation was the first from the three major video-game console makers. Nintendo and Sony will have similar events at E3, which runs through Thursday.